The extent to which stay-at-home mothers in Britain are penalised by the tax system was exposed last night.

One-earner couples with children are the only household type where Britons are shouldering a heavier tax burden than their counterparts in the developed world.

The extra tax they are paying is worth almost £160 a year for an average family.

By contrast, dual-income families in the UK pay far less tax than similar people in other countries, according to the report by the 34-nation Organisation for Economic Co-operation and Development.

In effect, it means that spouses who stay at home to raise their children are penalised – while those who go to work are rewarded.

The study will fuel the arguments of backbench Tories who want ministers to do more to recognise marriage in the tax system.

David Cameron has already promised a marriage tax break from next year under which a non-earner can transfer £1,050 of their tax-free personal allowance to a partner, allowing them to save around £200 a year.

But campaigners say it is not nearly generous enough.

The US, Canada, France, Germany, Denmark and Norway are among nations that reward the caring role of stay-at-home spouses far more than Britain.